Protection structure for outer shell of a hub

ABSTRACT

A protection structure for outer shell of a hub comprises: a hub and an outer shell mounted at one end of the hub, the outer shell is provided at one end close to the hub with an enlarged flange, on an outer peripheral surface of the outer shell are annularly and spaced-apart formed a plurality of splines and at least one positioning rib, at least at one side of each splines is disposed a protection structure whose material is different from that of the outer shell. By such arrangements, the protection structure can be assembled with the cassette to prevent the cassette touching the splines, thus preventing the damage of the outer shell of the hub.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a hub for bicycle, and more particularly to a protection structure for outer shell of a hub.

2. Description of the Prior Art

The existing bicycle hub for connecting the spokes and wheel is provided at one end thereof with an outer shell onto which a cassette can be mounted, and most of the outer shells sold on the market are made of aluminum alloy in order to reduce its weight, however, aluminum alloy is a kind of soft metal while the cassette is made of a hard metal steel, for the sake of structural rigidity.

To make it easy and quick for the splines of the aluminum alloy made outer shell of the hub to be engaged with the receiving hole of the steel cassette, it requires a predetermined amount of manufacturing allowance when manufacturing the outer shell and the cassette. However, the manufacturing allowance will cause slight impact between the cassette and the outer shell of the hub when the cassette drives the hub to rotate. On top of that, the cassette is made of hard metal while the outer shell of the hub is made of soft metal, so that, after a long time that the cassette drives and collides with the outer shell, the splines on the outer periphery of the outer shell of the hub will be damaged and worn down, reducing the engagement tightness therebetween.

The only solution to the above problem is to replace the outer shell of the hub, however, replacing the outer shell will cause more problems. For example, the high cost of the raw material, particularly, the aluminum price is increasing rapidly, therefore, the first result of replacing the damaged aluminum outer shell is the increase of raw material cost. Currently, there are two methods to assemble the cassette and the outer shell of the hub, one is to screw the outer shell to the hub, as mentioned above, so that the outer shell can be replaced separately. The other method is that the outer shell is integrally formed with the hub, as a result that the outer shell must be replaced together with the hub, thus further increasing the raw material cost.

Since the raw material price is increasing rapidly, the total cost will be reduced considerably if any of the parts of the product is replaced with low cost material, and it will has a great influence on the competitiveness of the product. In this regard, international standard specifies the width of the splines of the outer shell and the specification of the receiving hole of the cassette, however, the competitiveness of the hub product will greatly be improved if the amount of aluminum material used for forming the aluminum splines of the outer shell of the hub can be effectively reduced.

The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.

SUMMARY OF THE INVENTION

The primary object of the present invention is to provide a replaceable outer shell of a hub which is capable of preventing the damage of the splines of the outer shell of the hub.

The secondary object of the present invention is to provide an economic outer shell of a hub which reduces the amount of material used.

To achieve the above object, a protection structure for outer shell of a hub in accordance with present invention comprises: a hub and an outer shell mounted at one end of the hub, wherein the outer shell is provided at one end close to the hub with an enlarged flange, on an outer peripheral surface of the outer shell are annularly and spaced-apart formed a plurality of splines and at least one positioning rib, at least at one side of each splines is disposed a protection structure whose material is different from that of the outer shell. By such arrangements, the protection structure can be assembled with the cassette to prevent the cassette touching the splines, thus preventing the damage of the outer shell of the hub.

In addition, the steel legs are disposed beside and cooperate with the splines of the aluminum outer shell of the hub to form the width which equals the width of the slots of the cassette. In general, the amount of aluminum material used in the splines of the outer shell of the hub is only ⅔ or ½ the amount used in the conventional structure, plus the steel protection structure, which not only protects the outer shell of the hub but also saves the aluminum consumption.

The present invention will become more obvious from the following description when taken in connection with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiments in accordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of a protection structure for outer shell of a hub in accordance with a first embodiment of the present invention;

FIG. 2 is an assembly view of the protection structure for outer shell of a hub in accordance with the first embodiment of the present invention;

FIG. 3 is a cross sectional view of the protection structure for outer shell of a hub in accordance with the first embodiment of the present invention;

FIG. 4 is an exploded view of a protection structure for outer shell of a hub in accordance with a second embodiment of the present invention;

FIG. 5 is a perspective view of a protection structure for outer shell of a hub in accordance with a third embodiment of the present invention; and

FIG. 6 is an exploded view of a protection structure for outer shell of a hub in accordance with a fourth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be clearer from the following description when viewed together with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiment in accordance with the present invention.

Referring to FIGS. 1-3, a protection structure for outer shell in accordance with a preferred embodiment of the present invention comprises: a hub 10, an outer shell 20, and a cassette 30 to be mounted on the shell 20. The hub is of a conventional structure, further explanation is omitted.

The main improvement of the present invention lies in the outer shell 20 of the hub.

The cylindrical outer shell 20 is made of lightweight aluminum (such as aluminum alloy) or can be made of more advanced lightweight composite material (such as carbon fiber). In this embodiment, the outer shell 20 of the hub is made of aluminum alloy for example and comprises an outer peripheral surface 21, formed at the end of the outer peripheral surface 21 close to the hub is an enlarged flange 22, and on the outer peripheral surface 21 are equidistantly and annually arranged plural splines 211 and at least one positioning rib 212 with a width smaller than that of the splines 211. The positioning rib 212 and the splines 211 are extend from the position close to the free end of the outer shell 20 of the hub to the flange 22, and the width of the splines 211 is far smaller than the international standard size (for example ⅔ or ½ of the international standard size).

The steel cassette 30 is provided with an axial hole 31 in an inner surface of which are defined the number of slots 32 and positioning groove 33 as the splines 211 and positioning rib 212, so that the splines 211 and the positioning rib 212 are to be engaged with the slots 32 and the positioning groove 33 to assemble the cassette 30 onto the outer shell 20 of the hub.

In addition, to solve the problem that the splines 211 will be worn off by the collision between the splines 211 of the aluminum outer shell 20 and the cassette 30, the present invention provides a protection structure which covers the outer shell 20 of the hub.

The protection structure is made of hard metal, such as steel, which is different from the aluminum (or composite material) made outer shell of the hub. There are four embodiments of the protection structure.

The first embodiment is shown in FIGS. 1 and 2, the steel protection structure comprises a ring-shaped body 41 and a plurality of annularly arranged and spaced-apart flat legs 42 extending from the ring-shaped body 41. The legs 42 each have an arc-shaped inner surface with a radian corresponding to the radius of curvature of the ring-shaped body 41. The number of the legs 42 is equal to the splines 211, and a diameter of a circle defined by free ends of the legs 42 is slightly smaller than that of a circle defined by the other ends of the legs 42 where they are connected with the ring-shaped body 41 and is also smaller than the diameter of the outer shell 20 (Or the circular space defined by the legs 42 can also have a constant diameter), in other words, the legs 42 define a cone which tapers from one end to the other, so that, during the course of being assembled onto the outer shell 20 of the hub, the free end of the circular space defined by the legs 42 opens wide slightly, and when the ring-shaped body 41 of the protection structure is pushed to the flange 22, the legs 42 will be pressed closely against the outer shell of the hub by their elasticity in such a manner that one lateral edge of the respective legs 42 is abutted closely against the splines 211.

A second embodiment is shown in FIG. 4, the steel protection structure takes the form of flat legs 52 and the number of protection structure is the same as the splines 211. One lateral side of the respective legs 52 abutting against the splines 211 is a vertical surface, and the other lateral surface opposite to the vertical surface is an arc-shaped surface. The legs 52 each have an arc-shaped inner surface 521 which closely conforms to the outer peripheral surface 21 of the outer shell 20. On the arc-shaped inner surface 521 are formed two spaced apart semi-circular protrusions 522 (the number of the semi-circular protrusions 522 can be varied as required, the more protrusions 522, the more stable the engagement will be, and it requires at least one semi-circular protrusion). In the outer surface 21 of the outer shell 20 adjacent to each of the splines 211 are formed the same number of concaves 213 as the legs 52, through the engagement of the semi-circular protrusions 522 with the concaves 213, the flat legs 52 can be detachably mounted on the outer shell 20 to protect the splines 211.

A third embodiment is shown in FIG. 5, wherein the steel protection structure takes the form of flat legs 62 and the number of protection structure is the same as the splines 211. Each of the legs 62 has an arc-shaped inner surface 621 closely conforms to the outer peripheral surface 21 of the outer shell 20 and have a relatively thin guiding edge 622 to be engaged with a guiding groove 214 of the respective splines 211, so that the flat legs 62 can be detachably mounted on the outer shell 20 to protect the splines 211 by pushing the guiding edge 622 into place along the guiding groove 214.

A fourth embodiment is shown in FIG. 6, wherein the steel protection structure comprises a ring-shaped body 71 and the same number of flat legs 72 as the splines 211. Around the inner surface of the ring-shaped body 71 are formed a plurality of slots 711 penetrating through the axial thickness of the ring-shaped body 71 and a plurality of grooves 712 which are located in a non-penetrating manner beside the slots 71, and the position and number of the slots 711 correspond to that of the splines 211. The legs 72 each have an arc-shaped inner surface 721 closely conforms to the outer peripheral surface 21 of the outer shell 20. When the ring-shaped body 71 is inserted onto the outer shell 20, the legs 72 can be inserted in the grooves 712 and the splines 211 can be inserted through the slots 711 of the ring-shaped body 71.

With detachably mounted on the outer shell of the hub, the present invention achieves the following advantages:

First, with the protection structure detachably mounted onto the outer shell of the hub, the steel legs 42, 52, 62 and 72 can be engaged with the slots 32 of the cassette 30, so that, during rotation, the cassette 30 drives and collides with the steel legs 42, 52, 62 and 72, thus protecting the aluminum splines 211 from being damaged.

Second, after the outer shell 20 is driven and collided by the steel cassette 30 for a long period of time, the only element which is probably damaged is the protection structure, and the protection is low cost as compared to the aluminum material and detachably attached to the hub, so it can be replaced conveniently and the hub 20 can still be used, unlike the conventional art that the outer shell of the hub will be worn off and replaced together with the hub at regular intervals.

Third, the steel legs 42, 52, 62, 72 are disposed beside and cooperate with the splines 211 of the aluminum outer shell 21 of the hub to form the width which equals the width of the slots 32 of the cassette 30. In general, the amount of aluminum material used in the splines of the outer shell of the hub is only ⅔ or ½ the amount used in the conventional structure, plus the steel protection structure, which not only protects the outer shell of the hub but also saves the aluminum consumption.

While we have shown and described various embodiments in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention. 

1. A protection structure for outer shell of a hub, comprising a hub and an outer shell mounted at one end of the hub, the outer shell being provided at one end close to the hub with an enlarged flange, on an outer peripheral surface of the outer shell being annularly and spaced-apart formed a plurality of splines and at least one positioning rib, at least at one side of each splines being disposed a protection structure whose material is different from that of the outer shell.
 2. The protection structure for outer shell of a hub as claimed in claim 1, wherein the outer shell is made of aluminum and the protection structure is made of steel, the protection structure comprises a ring-shaped body and a plurality of annularly arranged and spaced-apart flat legs extending from the ring-shaped body, so that the metal protection structure is detachably mounted onto the outer shell in such a manner that the ring-shaped body of the protection structure is abutted against the flange of the outer shell, and the legs are abutted against one lateral side of the respective splines.
 3. The protection structure for outer shell of a hub as claimed in claim 2, wherein a diameter of a circle defined by free ends of the legs is slightly smaller than that of a circle defined by the other ends of the legs where they are connected with the ring-shaped body and is also smaller than a diameter of the outer shell.
 4. The protection structure for outer shell of a hub as claimed in claim 1, wherein the outer shell is made of aluminum and the protection structure is made of steel, the steel protection structure takes the form of flat legs as the splines and the number of protection structure is the same as the splines, on the flat legs are formed protrusions to be engaged in an outer surface of the outer shell, so that the legs are mounted to the outer surface of the outer shell.
 5. The protection structure for outer shell of a hub as claimed in claim 1, wherein the outer shell is made of aluminum and the protection structure is made of steel, the steel protection structure takes the form of flat legs and the number of protection structure is the same as the splines, each of the legs has a guiding edge to be engaged with a guiding groove of the respective splines, so that the flat legs can be detachably mounted on the outer shell to protect the splines by pushing the guiding edge into place along the guiding groove.
 6. The protection structure for outer shell of a hub as claimed in claim 1, wherein the outer shell is made of aluminum and the protection structure is made of steel, the steel protection structure comprises a ring-shaped body and the same number of flat legs as the splines, around an inner surface of the ring-shaped body are formed a plurality of slots penetrating through an axial thickness of the ring-shaped body and a plurality of grooves which are located in a non-penetrating manner beside the slots, and the position and number of the slots correspond to that of the splines, when the ring-shaped body is inserted onto the outer shell, the legs can be inserted in the grooves and the splines can be inserted through the slots of the ring-shaped body. 